Study on the kinetics and reaction mechanism of low-temperature oxidation of lignite with different coalification

•Lignite with different transmittance can be categorized into two types.•The oxidation mechanism of type Ⅰ lignite is –OH, –CH2–, and –CH3 → HO–R–OH → –CHO.•The oxidation mechanism of type Ⅱ lignite is –OH, –CH2–, and –CH3 → –OOH → –COOH.•Different measures against oxidation are required for different type of lignite. The differences in the coalification of lignite result in noticeable variations in the processes of its low-temperature oxidation. Consequently, this study utilizes thermogravimetric analysis and in-situ FTIR to investigate the oxidation kinetics and reaction mechanisms of lignite with different transmittance (PM). For lignite with PM